This invention relates to expansion gap assemblies for refractory lined vessels such as gasifiers and more particularly to a novel self-anchoring expansion gap assembly for a gasifier.
Partial oxidation gasifiers of the type shown in U.S. Pat. Nos. 2,809,104 and 5,484,554 are used for processing carbonaceous fuels, including coal, petroleum coke, gas and oil to produce gaseous mixtures of hydrogen and carbon monoxide, such as coal gas, synthesis gas, reducing gas and fuel gas. Typical gasifier operating temperatures can range from approximately 2200xc2x0 F. to 3000xc2x0 F. Operating pressures can range from 10 to 200 atmospheres.
The housing of a gasifier usually includes an outer steel shell or vessel that is lined on the inside with one or more layers of insulating and refractory material such as fire clay brick also referred to as refractory brick or refractory lining.
It is well known that refractory brick will expand as it heats up from ambient temperature to the operating temperature of the gasifier.
If no provision is made for heat expansion of the refractory lining in the gasifier there is a likelihood that the gasifier shell, which does not expand at the same rate as the refractory brick, will rupture as the brick expands. Another potential heat expansion problem is that a dome of refractory brick at an upper interior portion of the gasifier shell will bow or deflect resulting in a collapse of the refractory structure. Therefore, expansion gaps are usually provided for the refractory lining particularly at the upper interior portion of the gasifier to take up the heat expansion of the refractory brick.
The gasifiers in the previously referred to patents can operate with an annulus type feed injector such as shown in U.S. Pat. Nos. 4,443,230 and 4,491,456. The feed injector is usually located at a top portion of the gasifier, at a reduced neck opening, and serves to introduce pumpable slurries of carbonaceous fuel into the gasifier. The slurries of carbonaceous fuel are directed downwardly into a reaction chamber within the gasifier along with oxygen containing gases for partial oxidation.
To facilitate installation of the feed injector an annular flange, also referred to as a middle flange, is usually provided at the top neck opening of the gasifier. The middle flange forms a mounting surface for the feed injector. The feed injector shown in U.S. Pat. No. 5,484,559 includes a mounting flange that lies on the middle flange in an arrangement that substantially closes off the top portion of the gasifier. Such mounting arrangement of the feed injector helps maintain a pressurized environment in the gasifier.
When the feed injector is in operating position on the gasifier it extends downwardly in a centralized position from the top neck opening of the gasifier such that there is an annular space between the body portion of the feed injector and the surrounding refractory lining.
It is known to provide an expansion gap for the refractory lining above a top surface of the refractory brick at the upper interior portion of the gasifier below the top opening of the gasifier shell. This expansion gap is thus a space defined between the middle flange that supports the feed injector and the top surface of the refractory brick. However, the expansion gap exposes an inner surface of the gasifier shell which, if left unprotected, would result in overheating of the gasifier shell at the expansion gap.
In order to protect the exposed inner surface of the gasifier shell it is known to provide in the expansion gap a refractory expansion gap assembly, formed of compressible refractory insulating material. The expansion gap assembly, in uncompressed condition is normally thicker than the expansion gap, and is compressed against the top surface of the refractory brick when the middle flange is installed on the top neck portion of the gasifier.
However, during preheating procedures and gasification a vacuum condition develops in the annular space that surrounds the body of the feed injector. The vacuum condition tends to draw or pull out the expansion gap assembly away from the expansion gap in a downward direction into the reaction chamber of the gasifier. The vacuum force pullout effect on the expansion gap assembly is also referred to as vacuum pullout of the expansion gap assembly.
An unfortunate result of vacuum pullout of the expansion gap assembly is that the interior surface of the gasifier shell becomes exposed at the expansion gap and is vulnerable to overheating failure without the insulation protection provided by the refractory expansion gap assembly.
It is thus desirable to provide a self-anchoring refractory expansion gap assembly that resists vacuum pullout from the expansion gap of a gasifier.
Among the several objects of the invention may be noted the provision of a novel self-anchoring expansion gap assembly for a gasifier, a novel self-anchoring expansion gap assembly that can be locked into an expansion gap of a gasifier, a novel self-anchoring expansion gap assembly for a gasifier that includes a peripheral bulge portion that resists vacuum pullout of the expansion gap assembly, a novel self-anchoring expansion gap assembly for a gasifier that is formed of compressible and relatively incompressible refractory material, with the relatively incompressible refractory material being positioned proximate the outer periphery of the expansion gap assembly, a novel self-anchoring expansion gap assembly for a gasifier that includes compressible refractory material wrapped around relatively incompressible refractory material, a novel self-anchoring expansion gap assembly that includes compressible refractory material positioned on relatively incompressible refractory material, a self-anchoring expansion gap assembly for a gasifier that includes compressible refractory material and relatively incompressible refractory material wrapped in a sheath to form an integral package, a self-anchoring annular expansion gap assembly having compressible refractory material formed of a plurality of sectors of an annulus and folded onto a coil of relatively incompressible refractory material, a self-anchoring annular expansion gap assembly for a gasifier having a one piece compressible refractory insulating structure folded around a coil of relatively incompressible refractory material, and a novel method of preventing vacuum pullout of an expansion gap assembly from a gasifier.
Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.
In accordance with the invention a self-anchoring expansion gap assembly for a gasifier includes a substantially annular insulating blanket structure formed of compressible refractory material and a coil of relatively incompressible refractory rope positioned proximate the outer periphery of the insulating blanket.
The expansion gap assembly is disposed in an annular expansion gap of a gasifier which expansion gap includes an annular peripheral channel. The coil of refractory rope of the expansion gap assembly is thus receivable and lockable in the annular channel of the expansion gap.
Under this arrangement the coil of rope and the insulating blanket structure can receive an axial compression force such that the coil of rope and a portion of the insulating blanket are forced into the annular channel of the expansion gap to thereby lock the expansion gap assembly into the annular channel. The locking in of the compressible refractory blanket structure and the relatively incompressible refractory rope in the annular channel prevents the expansion gap assembly from being pulled away from the expansion gap of the gasifier.
In some embodiments of the invention the expansion gap assembly includes a compressible annular refractory portion that is composed of a plurality of sectors of an annulus. The sectors of compressible refractory insulating material are folded around a one piece coil of the refractory rope.
The compressible refractory insulating material can be a laminate of two different insulating materials. Preferably one compressible layer is formed of a ceramic refractory blanket and the other compressible layer can be formed of ceramic paper or ceramic cloth.
In one embodiment of the invention the ceramic paper or cloth layer constitutes the inside layer of the folded laminate and thus makes direct contact with the refractory rope.
In other embodiments of the invention the ceramic paper or ceramic cloth constitutes the outside layer material of the folded laminate. Thus the ceramic refractory blanket makes direct contact with the refractory rope. In another embodiment of the invention the expansion gap assembly includes an annular sheath of stainless steel mesh to form an integral package that can be installed as a unit.
In some embodiments of the invention the coil of refractory rope is wound into a single coil. In other embodiments of the invention the coil of refractory rope can be wound into a double coil or a triple coil as desired.
In a further embodiment of the invention the compressible insulating blanket structure can comprise a single non-folded layer of refractory material placed on a coil of rope and wrapped in an inner annular sheath of ceramic cloth and an outer annular sheath of a high temperature metal alloy such as stainless steel mesh or Inconel(copyright) mesh to form an integral package that can be installed as a unit.
In another embodiment of the invention the expansion gap assembly can be formed of one piece compressible refractory layers that are folded around a coil of rope. This embodiment can also, if desired, be surrounded by an inner annular sheath of ceramic cloth and an outer annular sheath of a high temperature metal alloy such as stainless steel mesh or Inconel(copyright) mesh.
In all embodiments of the invention the self-anchoring expansion gap assembly is thicker, when compressed, than the expansion gap and includes a peripheral bulge portion that aligns with an annular channel of a gasifier. The peripheral bulge portion includes a peripheral portion of the compressible refractory blanket structure and the relatively incompressible refractory rope.
The middle flange, when positioned on the gasifier, covers the expansion gap and compresses the expansion gap assembly. The peripheral bulge portion of the expansion gap assembly is thus forced into the annular channel of the expansion gap to lock the expansion gap assembly in position. Locking in of the expansion gap assembly prevents it from being subject to vacuum pullout when the gasifier is in operation.
The invention further includes a method of preventing vacuum pullout of an expansion gap assembly. The method includes providing an annular groove in the refractory brick lining of the gasifier shell at an upper portion of the gasifier and forming a self-anchoring expansion gap assembly as previously described. The method further includes positioning the expansion gap assembly such that the coil of refractory rope is aligned with the annular groove of the gasifier and compressing the expansion gap assembly to lock the peripheral bulge portion of the expansion gap assembly, including the coil of rope into the annular groove.
The method further includes forming the annular compressible blanket portion of the expansion gap assembly of substantially radial sectors of an annulus.
The invention accordingly comprises the constructions and methods hereinafter described, the scope of the invention being indicated in the claims.